Former commissioner of the US Food and Drug Administration, Dr Scott Gottlieb said on Tuesday that he would not take the Russian vaccine outside of a clinical trial.
"I wouldn't take it, certainly not outside of a clinical trial right now," Gottlieb said on CNBC, reports the CNN.
"It appears that it's only been tested in several hundred patients, at most. There's some reports that it's been in as few as 100 patients."
Gottlieb explained that it was an adenoviral vector vaccine, which is "not a trivial vaccine in terms of the technical complexity that goes into manufacturing."
China is also developing an adenoviral vaccine, which is in clinical trials in Canada, but early data from that vaccine isn't very encouraging, he said.
There are more things that can go wrong from a safety standpoint with this type of vaccine, Gottlieb said, including that people could have a reaction to the viral vector itself.
"It's not clear how efficacious the Russian vaccine is going to be and whether or not people have some prior immunity to the adenovirus that they're using to deliver the coronavirus gene sequence," he said.
Gottlieb said that at this point he was worried about both the safety and the efficacy of the Russian vaccine. Something that has only been tested in several hundred patients, which is effectively a phase one clinical trial, is not something you would want to take outside of a clinical trial where you are closely monitored, he said.
"In a lot of these situations, you might only get one shot at taking a vaccine within a season, so if you put a vaccine on the market that's not efficacious, it's going to be hard to revaccinate the population, so you want to make sure it works," he said.
Gottlieb also tweeted a clip of his interview with CNBC, with the caption: "Russia was reported to be behind disinformation campaigns to sow doubts in US about our Covid vaccines; and today's news that they "approved" a vaccine on the equivalent of phase 1 data may be another effort to stoke doubts or goad US into forcing early action on our vaccines."
Russia "certainly not ahead" of US
Dr Gottlieb also said that Russia is not ahead of the US when it comes to vaccine development.
"I think in terms of their development right now, they're a little bit behind where we are with the vaccines that we have," Gottlieb said.
US vaccines are now in phase three trials, having cleared phase one and phase two studies, being tested on hundreds, or in some cases a couple of hundred patients, which is about where Russia is right now, according to Gottlieb.
The amount of people who the Russian vaccine has been tested in means that it has cleared the equivalent of a phase one trial, but still needs to be evaluated in a large-scale clinical trial, Gottlieb said.
He said it was unclear to him what it meant for Russia to start giving some kind of preliminary approval to start vaccinating people outside of a clinical trial. Gottlieb added they might be trying to do a registry, where volunteers who take the vaccine outside of a trial who are then followed, but it's not really cleared for general use in the market.
"There might be a little bit of semantics going on in terms of how they're treating this from a regulatory standpoint," Gottlieb said.
"So, they are claiming that it's fully approved, but it's not really fully approved. They are certainly not ahead of us, and we certainly wouldn't allow a vaccine to be used for mass distribution at this point based on the data that we have in hand. We just don't know that the vaccines are safe and effective at this point," Gottlieb added.